Puncture-proof tube and process of producing same.



W. S. OBERFELDER.

P UNGTURE PROOF TUBE AND PROCESS OF PRODUCING SAME.

APPLICATION FILED SEPT-5| i916.

Patented Oct. 23, 1917.

2 SHEETS-SHEET I w. s. OBERFELDER.

PUNCTUR-E PROOF TUBE AND PROCESS OF PRODUCING SAME.

APPLICATION FILED SEPT. 5. 1916.

1,244,936. Patented 001;. 23,1917.

2 snzETs-snuir 2.

WALTER S. OIBERFELDER, OF CHICAGO, ILLINOIS.

runo'rlmn-rnoon TUBE Ann rnoonss or PRODUCING SAME.

Specification of Letters Patent. Patented (Pet. 23, 19117..

Application filed September 5, 1916. Serial No. 118,340.

To all whom it may concern-:-

Be it known that LWALTER S. OBERFELDER,

- a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented'certain new and useful Improvements in Puncture Proof Tubes and Processes of Producing Same, of which the following is the specification.

This invention relates to tube construction, and particularly to a method of mak- 1ng tires or inner tubes adapted to auto. matically close punctures in said tires or inner tubes.

It is an object of the invention to equip tires or inner tubes with a heavy layer of cheap rubber, or like material, so constructed as to automatically become compressed upon its inner surface when the tube is in condition for use and thus become self healing or self-closing.

It is another object of the invention to cheapen the manufacture of self-healing tires by devising a method for using a lower grade rubber therein.

It is another object of the invention to devise a method whereby the self-healing layer of my improved tube will be subjected to a double compressing action.

Other objects and advantages of the invention will appear as the description to follow proceeds.

In the drawings, p

Figure 1 is a perspective view showing the various layers of my tube.

Fig. 2 is a cross sectional view in one of its stages;

Fig. 3 is a cross sectional view of the tire blank in completed form; v

Fig. 4 is a cross sectional view of a modified form of the inflated and completed irmer tube within the outer casing;

F'g. 5 is a perspective view of a blank applicable for the purposes of my invention Fig. 6 is an elevation of an inner tube constructed in accordance with my invention;

Fig. 7 is a cross sectional view of a modification of the invention;

Fig. 8 is a cross sectional view modification of the invention.

I am fully aware that it has been heretofore proposed to provide a layer of soft rubber which is made under compression so as to have a self-sealing action. In .all of such tubes which are at all practicable, however, mechanical compression means, such as layers of fabric, incorporatedinto the of another tube, are employed to obtain the compression. This is objectionable, because the fabric employed is frequently broken off, is very expensive to incorporate in the body of the rubber, and when so incorporated introduces a tendency to leak because the finest cotton fiber, owing to its cellular nature, provides a pathway or channel along which air will flow under the high pressure employed in tubes.

Other tubes of this same general class and in the prior art are made by first making a tube having a soft rubber layer therein and then turning said tube inside out, the thick layer of rubber being made of two or more layers of difi'erent classes of rubber which are very expensive due to the quality of rubber used.

My invention has none of these defects and disadvantages, because the compression by it is obtained solely by the shape given to the inner tube by its inflation within an outer casing, and furthermore, because by reason of the manner of manufacture a double compression is obtained when the tube is placed inside an outer tube and in- In the manufacture of my tube, I take a strip of rubber 1, long and wide enough to form an inner tube. Upon this strip of rubber I vulcanize a heavy, thick strip of compressible material 2, as for instance, soft- '1. Over the rubber layer l, I next secure a narrow strip of canvas, or otherfabric, 5.

This layer is not provided to assist in anyway m obtaining compression but only to prevent punctures from spreadlng 1n the outer layer. The fabric 5 may be cemented upon the tire and may sometimes be applied after the precedinglayers have been made into a complete tube. V V

. The built-up structure shown 1n Flg. 1 is next formed 1nto a tube upon a mandrel, which is perfectly flat, the longitudinal edges lbeing united and'the ends 1" are thereafter unitedto form a complete tube.-

It is to be particularly noted that, as the tube is made fiat, the bending involved in first forming a tube and in thereafter uniting the ends of that tube will serve to give a double compression upon the inner side of the layer 2, when the tube is inflated inside an outer casing, thus serving adequately to close all punctures. It is further to be noted that this result comes from the shape of the tube itself when inflated after being placed inside an outer tube, and not because of the presence of the fabric layer or because it was turned inside out. The building up of this tube from flat strips entirely isresponsible for this result.

In Fig. 1 ll show a cross section of a completed inner tube in acting position without the fabric layer 5, wherein .it will be seen that the inner region 2 of the soft or sponged rubber layer, or equivalent substance, 2, is tightly compressed The outer strip'l and inner strip 1 in this modification are the same as those shown in Fig. 1, the fabric strip 5 merely being omitted.

lln Fig. 2 I show a modification of the invention, in which the inner tube is composed entirely of the layer 1 and the layer 2 directly vulcanized thereto, the layer 4c of Fig. 1 being dispensed with. In this modification, the fabric strip 5 may be applied either after or before the tube has been formed, or left out.

In Fig. 5, T disclose a strip 2 0i compressible material such as sponge rubber or the like which can be vulcanized to a completed tube, the result appearing in Fig. 6, in which it will be particularly noted that the fiat strip 2 when secured upon the collapsed fiat inner tube 7, assumes the form shown when this inner tube is placed inside a tire involving the curvatures above alluded to, and the corresponding compressions will necessarily take place.

In Fig. 7, I show another way of constructing the tube of my invention, which consists in forming the layer 8, of rubber and the cheaper layer of sponge rubber or the like-9 in one piece by using an appropriately. formed blank of rubber, thickened in the middle, and sponging the upper part of the thickened portion. This piece of rubber, as it stands, may be formed into an inner tube with the resultin compressions as above described and will %)9 ready for use without further treatment. A fabric layer 5 should preferably be applied to prevent punctures from spreading. This la yer may be cemented on.

In Fig. 8 is a modification in which the sponge rubber layer 9', which, in this instance is shown as formed integrally with the'high-grade rubber layer 8', is originally formed in curved or gutter shape. In forming the tube, it-is bent oppositely from the curvature shown in Fig: 8, thereby increasing the compression along the inner side near-nae thereof when the tube is placed within an outer casing and inflated. This is the preferable form for large tires. Of course, it will be understood that the thickness of the soft rubber compressible layer may be varied in accordance with the size .of the tire and the demands to be made upon it. The term sponge rubber as employed in the specification is generic. The preferable form is fibered sponge rubber which cannot stretch but is compressible. While the application of sponge rubber for the purpose herein described is a feature of the invention, the invention broadly of course does not concern sponge rubber or even rubber, but rather the construction of a tire so as to automatically become puncture proof when inflated in a case for use, owing to its shape and that of the parts of which it is constructed and their relative arrangement Any material other than rubber havin the properties of rubber for the purposes of this invention might obviously be substituted for rubber without departing from the scope of the invention.

The difierent forms of tubes described may be made of diflerent kinds of rubber and then vulcanized or otherwise fastened together or the entire tube may be made in one operation.

T claim 1. A tube comprising a layer of rubber or the like, a heavy layer of soft, compressible material secured thereto, a layer of rubber or the like overlying said soft material and a narrow strip of fabric secured over said second layer of rubber or the like.

2. A tube comprisin a tube of highgrade rubber having a t ick strip of sponge rubber vulcanized thereupon in the tread region of the tube.

3. A tube made up of a flat strip of rubber, having pressible rubber attached thereto while the strips are ing afterward united at their longitudinal edges to form a tube and at their ends to form an annular tube or tire.

4. A tube made up of a flat strip of highgrade rubber, to which is vulcanized a heavy at strip of sponge rubber prior to forming the tube on a mandrel or the like, whereby the sponge rubber will be so located with respect to the tire as to be given a compression in two directions when the tire is made up and inflated.

5. An inner tube made of a flat strip of resilient material and a thick flat strip of re-1 silient material attached thereto.

6. A tread portion for tires of sponge or soft rubber having beveled longitudinal edges ada ted to be attached to the tread portion 0 inner tubes. I

1 7. An inner tube comprising layers, one of said layers being composed of a flat thick,

a fiat strip of thick, soft, comlaid flat, said combined strips berubber, said inner tube when uninflated being flat and comprising-parts normally fiat, but when inflated inside an outer tube acquiring an annular and tubular form Whereby double compression on the thick layer of rubber is obtained.

8. As an article of manufacture, a tube made up of a normally flat blank rubber or the like, including a strip of soft compressible material, said blank being united at its edges and its ends to form an annular closed tube suitable for use as an inner tube or the like, the bending operations involved in forming the annular closed tube causing said strips of soft compressible material to be compressed in two directions when the tube is inflated.

9. The method of making an inner tube which consists in'formin a flat blank having a strip of compressiib e material therein and a layer of elastic material substantially I tube which when inflated in a suitable casing will form an annular tube of circular cross section, whereby the compressible material therein will be compressed and serve to automatically seal up punctures.

In witness whereof, I hereunto subscribe my name to this specification in the presence of two witnesses. I

WALTER S. OBERFELDER.

Witnesses:

I. V. CURRAN, SEBASTIAN HrN'roN. 

